1. Field of the Invention
The subject invention relates to displays and more particularly to a hologram for removing aberrations generated by a mirror in an image viewed in a head-up automotive display.
2. Description of Related Art
Prior art holographic head-up displays have been associated with aircraft applications and have been relatively complex and expensive. See generally U.S. Pat. Nos. 4,447,128 and 3,885,095 assigned of record to Hughes Aircraft Company. In proposed head-up automotive displays, the windshield serves as a combiner mirror which generates aberrations in the viewed image. In conventional head-up displays, the source is matched to the aberrations of the combiner by adding complex relay optics between the source and the combiner to warp the intermediate image presented to the combiner. These relay optics typically have 7-10 elements, which are tilted, decentered and sometimes aspheric. They cost thousands of dollars and are bulky and heavy. Such an approach is clearly not suitable for a low cost automotive display that requires minimal space in the instrument panel.
Holographic procedures for forming holograms in general are well-known and can be found in known reference works, such as "Optical Holography" by Collier et al., Academic Press, New York, N.Y. (1971). However, to date such procedures have not been applied to automotive displays or to the problems of aberrations in such displays.